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Mallet Finger


Danielle Campagne

, MD, University of California, San Francisco

Last full review/revision Mar 2021| Content last modified Mar 2021
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Mallet finger is a flexion deformity of the fingertip caused by avulsion of the extensor tendon, with or without fracture, from the proximal end of the distal phalanx.

The usual mechanism is forced flexion of the distal phalanx, typically when hit with a ball. The extensor tendon may avulse part of the proximal aspect of the distal phalangeal bone (see figure Mallet finger). The avulsed part involves the articular surface.

Mallet finger

The extensor tendon is avulsed from the proximal end of the distal phalanx (top); sometimes the tendon avulses a piece of the distal phalangeal bone (bottom).

Mallet finger

Symptoms and Signs of Mallet Finger

The finger is usually painful and may be swollen and bruised immediately after the injury. Occasionally, blood collects under the nail (called subungual hematoma).

The affected dorsal interphalangeal (DIP) joint rests in a more flexed position than the other DIP joints and cannot be actively straightened but can easily be passively straightened, usually with minimal pain.

Diagnosis of Mallet Finger

  • Clinical evaluation

  • X-rays

Mallet finger can usually be diagnosed by examining the finger.

Anteroposterior, lateral, and usually oblique x-rays are taken. A fracture, if present, is usually visible on the lateral view. X-rays may be normal if only the tendon is torn.

Treatment of Mallet Finger

  • Splinting

  • Sometimes referral for surgical fixation

Treatment of Mallet finger is with a dorsal splint that holds the DIP joint in extension for 6 to 8 weeks; during this time, the tip cannot be allowed to flex (eg, when cleaning the finger).

Fractures that involve > 25% of the joint surface or that cause joint subluxation may require surgical fixation.

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